Protectors for electric circuits



Jan. 3i, 1967 A. J. FISTER 3,301,978

PROTECTORS FOR ELECTRIC CIRCUITS Filed sept. 2o, 1965 FG. l? 52) United States Patent O 3,301,978 PROTECTORS FOR ELECTRIC CIRCUITS Aloysius J. Fister, Overland, M0., assigner to McGraw- Edison Company, Elgin, Ill., a corporation of Delaware Filed Sept. 20, 1965, Ser. No. 438,444 3 Claims. (Cl. 20o-120) This invention relates to improvements in protectors for electric circuits. More particularly, this invention relates to improvements in electric fuses.

It is, therefore, an object `of the present invention to provide an improved electric fuse.

Electric fuses customarily have tubular housings of insulating material; and some of those fuses have relatively massive terminals at the ends of those housings. Those relatively massive terminals frequently have general-ly cylindrical portions which extend into the housings for the fuses and have generally flat portions which extend outwardly from those housings and are used to connect the fuses into the electrical circuits which they are to protect. Some of those relatively massive terminals are made by initially machining thick cylindrical discs, and then suitably bonding generally at portions to the outer faces of those discs. While it is relatively easy and inexpensive to initially machine the thick cylindrical discs and to bond the kgenerally flat portions to the outer faces of those discs, it is usually desirable to machine the peripheries of those discs after those `generally dat portions have been bonded to the outer faces of -those discs; and the machining of those peripheries necessitates a time-consuming and expensive manufacturing step. Other of those terminals are machined from metal cy-linders or rods; and the machining of those terminals from metal cylinders or rods produces a considerable amount of scrap metal and also requires a considerable amount of time. Still other of those terminals are initially made as castings, and are subsequently machined to the desired dimensions. Relatively massive tenminals that are made in these various ways are expensive, and they are usually quite heavy. It would be desirable to provide relatively massive terminals for electric fuses which could be made less expensively and of less weight. The present invention provides such terminals; and it is, therefore, an lobject of the present invention to provide relatively massive terminals for electric fuses which can be made inexpensive- Ily and which are relatively light in weight.

Other and further objects an-d advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description several preferred embodiments of the present invention are shown and described but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be 4defined by the appended claims.

In the drawing, FIG. 1 is a longitudinal sectional view through one preferred embodiment of electric fuse that is made in accordance with the principles and teachings of the present invention,

FIG. 2 is a sectional view through the electric fuse of FIG. 1, and it is taken along the plane indicated by the line 2-2 in FIG. 1,

FIG. 3 is a broken, lon-gitudinal sectional view through a second preferred embodiment of electric fuse that is made in accordance with the principles and teachings of the present invention,

FIG. 4 is an exploded view of the right-hand terminal used in the electric fuse of FIG. 3,

FIG. 5 is a broken, longitudinal sectional vie-w of yet another preferred embodiment of electric fuse that is made in accordance with the principles and teachings of the present invention,

FIG. 6 is an exploded view of the left-hand terminal of the electric fuse of FIG. 5,

FIG. 7 is a broken away, longitudinal sectional view through still another preferred embodiment of electric fuse that is made in accordance with the principles and teachings of the present invention, and

FIG. 8 is a perspective view of the right-hand terminal of the electric fuse of FIG. 7 before pin-receiving sockets are formed in the periphery of that terminal.

Referring to the drawi-ng in detail, the numeral 20` denotes the housing for the electric fuse shown in FIGS. 1 and 2; and that housing is made of insulating material and is cylindrical in configuration. A terminal is disposed within the left-han-d end of the housing 20; and that terminal includes a generally-flat portion 22 which has a reduced width inner end 23, and also includes washers 24, 26, 28 and 30 which are telescoped onto that reduced width inner end. The washers 24, 26 and 28 are identical in configuration-each of those washers having a cylindrical periphery and having a rectangular slot adjacent the center thereof to telescope snugly over the reduced width inner end 23 of the generally-flat portion 22. The washer 30 is similar to the washers 24, 26 and 28, but it differs from those washers by having a number of shall-ow, circumferentially-spaced indentations 32 formed inthe righthand face thereof. In forming the terminal which includes the generally-dat portion 22 and the washers 24, 26, 28 and 30, those Washers are telescoped onto the reduced width inner end 23 of the generally-dat portion 22, and then the exposed face of that reduced width inner end is struck by a staking -or similar tool to mechanical-ly lock lthose washers onto that reduced Width inner end. Thereafter, solder or some other suitable conductive material is used to electrically bond those -washers to each other and to the generally-flat portion 22.

A terminal also is disposed within the right-hand end Iof the housing 20; and that terminal includes a generallyflat portion 34 with a reduced Width inner end 35. The generally-flat portion 34 and the reduced width inner end 35 are identical to the `generally-flat portion 22 and the reduced width inner end 23. The reduced width inner end 35 of the generally-flat portion 34 accommodates washers 36, 38, 40 and 42; and those washers are similar to the washers 24, 26, 28 and 30. However, the washers 36, 38, 40 and 42 differ from the washers 24, 26, 28 and 30 in having openings therein which dene a passage 46. In forming the terminal which includes the generally-flat portion 34 and the washers 36, 38, 40 and 42, those washers are telescoped onto the reduced width inner end 35 of that generally-flat portion, and then the exposed face of that reduced width inner end is struck by a staking or similar tool to mechanically ylock those washers onto that reduced width inner end. Thereafter, solder or some other suitable conductive material is used to electrically bond the washers 36, 38, 40 and 42 to each other and to the generally-flat portion 34.

The shallow indentations in the inner face of the washer 42 are denoted by the numeral 44; and those indentations are in register with the shallow indentations 32 in the inner face of the washer 30. The shallow indentations 32 receive the left-hand ends of fusible conductors 50, and the shallow indentations 44 receive the right-hand ends of those fusible conductors; and solder is used to bond the ends of those fusible conductors to the confronting faces of the washers 30 and 42. While the fusible conductors 50 are shown as having a number of weak spots defined by generally rectangular notches, and while those fusible conductors are shown as having generally-cylindrical rivetlike masses of readily-fusible material thereon, those fusible conductors can have different configurations and can be made in different ways. The fusible conductors 50 will coact with the two terminals to constitute a readilyhandled sub-assembly; and that sub-assembly can readily be telescoped within theI housing 20 to occupy the position shown by FIG. 1. At such time, the washers 24, 26, 28 and 30 will closely engage the inner surfaces at the left-hand end of the housing 20, and the Washers 36, 38, -40 and 42 will closely engage the inner surfaces at the right-hand end of that housing. Pins, not shown, will extend through openings, not shown, in the housing 20 and seat in sockets, not shown, in the terminals to hold those terminals in assembled relation with that housing. The electric fuse can then be rested upon the outer end of the generally-fiat portion 22 of the terminal at the lefthand end of that housing; and then a suitable arc-quenching filler material 52 can be introduced into the passage 46. After the desired amount of the arc-quenching filler 52 has been introduced through the passage 46, a selftapping plug 48 can be seated within that passage to close and seal that passage.

The washers 24, 26, 28, 30, 36, 38, 40 and 42 can be punched out of a fiat sheet of metal such as copper or brass; and the generally-flat portions 22 and 34 can be punched out of a fiat strip of metal such as coppe-r or brass. The punching operations are inexpensive and are quickly accomplished, and they do not produce a sizable amount of waste. The assembling of the washers 24, 26, 28, 30, 36, 38, 40 and 42 with the reduced-width inner ends 23 and 35 of the relatively-flat portions 22 and 34 can be accomplished quickly and easily. The overall result is that the terminals of FIG. l can be much less expensive than previously-used relatively massive terminals for electric fuses.

Referring to FIGS. 3 and 4, the numeral 56 denotes the housing for another electric fuse; and that housing is made of insulating material and is cylindrical in configuration. A terminal is disposed within the left-hand end of that housing; and that terminal has a generally-fiat portion 58 with a reduced width inner end. Washers 60, 62, 64 and 66 are telescoped onto that reduced width inner end, and those washers are mechanically-secured and electrically-bonded to that reduced width inner end. The washers 60, 62 and 66 are identical to the washers 24, 26 and 30 of FIG. l; and the washer 64 is similar to, but has a smaller diameter than, the washer 28 of FIG. 1. The smaller diameter Washer 64 coacts with the large diameter washers 62 and 66 to define an annular recess for an O- ring 70.

A terminal is disposed within the right-hand end of the housing 56; and that terminal includes a generally-flat portion 72 with a reduced width inner end and also includes washers 74, 76, 78 and 80. These washers are telescoped onto the reduced Width inner end of the generally-fiat portion 72; and those washers are mechanically-secured and electrically-bonded to that generally-fiat portion. The Washers 74, 76 and 80 are identical to the washers 36, 38 and 42 in FIG. l; and the washer 78 is similar to, but has a smaller diameter, than the washer 40 of FIG. 1. The smaller diameter washer 78 coacts with the larger diameter Washers 76 and 80 to define an annular recess for an O-ring 84. Shallow, circumferentially-spaced indentations 68 are provided in the inner face of the washer 66, and shallow, circumferentially-spaced indentations 82 are provided in the inner face of the washer 80. The indentations 68 and 80 are in register with each other; and they accommodate the ends of fusible conductors 90. The washers 74, 76, 78 and 80 have openings therein which define a passage 86; and a self-tapping plug 88 can be disposed within that passage.

Thevends of the fusible conductors 90 arey set within the shallow indentations 68 and 82 in the washers 66 and 80 and are then bonded to those washers by solder. Thereafter, those fusible conductors will coact with the terminals to constitute a sturdy sub-assembly; and that sub-assembly can be telescoped within the housing 56 to occupy the position shown by FIG. 3. Pins, not shown, will extend through openings, not shown, in the housing 56 and seat in sockets, not shown, inthe terminals to hold those terminals in assembled relation with that housing. At such time, the electric fuse can be rested on the outer end of the generally-flat portion 58 of the terminal disposed in the left-hand end of the housing 56; and then arc-quenching filler material 92 can be introduced through the passage 86. After the desired amount of arc-quenching filler material 92 has been introduced, the self-tapping plug 88 can be set within the passage 86 to close and seal that passage.

Referring to FIGS. 5 and 6, the numeral 96 denotes the housing for another electric fuse; and that housing is made of insulating material and is cylindrical in configuration. A terminal is disposed Within the left-hand end of that housing; and that terminal includes a generally-fiat portion 98 with a reduced width inner end and also includes washers 99, 100,104 and 108. The washers 99 and 108 are identical to the washers 24 and 30 in FIG. l; and the washers 100 and 104 are similar to the Washers 62 and 64 in FIG. 3 but have weight-reducing openings 102 and 106 therein. Specifically, the washer 100 has two weight-reducing openings 102 intermediate the periphery thereof and the central opening which telepscopes over the reduced-width inner end of the generally-flat portion 98. Similarly, the washer 104 has two weight-reducing openings 106 intermediate the periphery thereof and the central opening which telescopes over the reduced-Width inner end of the generally-fiat portion 98.

A terminal is disposed within the right-hand end of the housing 96; and that terminal includes a generally-flat portion 112 with a reduced-width inner end and also includes washers 113, 114, 118 and 122. The terminal which is disposed within the right-hand end of the housing 96 is substantially identical to the terminal which is disposed within the left-hand end of that housing-that terminal differing from the terminal disposed within the left-hand end of the housing 96 by having an opening 126 in the Washer 113 and by having a corresponding opening in the washer 122. Those openings coact with the upper openings 116 and 120 in the washers 114 and 118 to constitute a passage through which arc-quenching filler material 132 can beintroduced into the housing 96. A self-tapping plug 128 can be set within the opening 126 in the Washer 113 to close and seal that opening. The reduced diameter Washers 104 and 118 coact with the larger diameter adjacent washers to define annular recesses in which O- rings 134 and 136 can be disposed. Those O-rings will coact with the inne-r surface of the housing 96 to provide seals for the fuse.

The indentations in the inner face of the washer 108 are in register with the indentations 124 in the inner face of the washer 122. Those indentations will receive the ends of fusible conductors and solder will bond those fusible conductors to the terminals. Pins, not shown, will extend through openings, not shown, in the housing 96 and will seat in sockets, not shown, in the terminals to hold those terminals in assembled relation with that housing.

Referring to FIGS. 7 and 8, the numeral 140 denotes a housing; and that housing is made of insulating material and is cylindrical in configuration. A terminal is disposed within the left-hand end of the housing and that terminal includes 'a generally-flat portion 142 with a reduced-width inner end and also includes washers 144, 146, 148, 152, and 153 which telescope over that reduced width inner end. The washers 144, 146, 148 and 152 are identical to the washers 24, 26 and 28 of FIG. 1. The washer 153 is thinner than any of the Washers 144, 146, 148 and 152, and its periphery is frusto-conical in configuration; and hence that washer is cup-like in form. The Washers 144, 146, 148, 152 and 153 are mechanically-secured and electricallybonded to the generally-fiat portion 142.

A terminal is disposed within the right-hand end of the housing 140; and that terminal includes a generallyflat portion 154 with a reduced-width inner end and also includes Washers 156, 158, 160, 164 and 166. The washers 156, 158, 160, 164 and 166 are identical to the washers 144, 146, 148, 152 and 153; and, as a result, the two terminals for the fuse of FIG. 7 are identical.

The cup-like Washers 153 and 166 of the terminals for the fuse of FIG. 7 accommodate tubular washers 170 and 171 which extend inwardly into a tube 168 of a ceramic material; and those tubular washers accommodate the outer ends of a fusible conductor 172 which is disposed Within that tube. The opposite ends of the tube 168 are provided with metallized coatings; and, after the tubular washer 170 is disposed within the lefthand end of the tube 168 and the left-hand end of the fusible conductor 172 is disposed within that tubular washer, solder is used to bond that tubular washer to the metallized surface on the left-hand of the tube 168 and to the left-hand end of the fusible conductor 172. Thereafter, the tube 168 is set on its left-hand end and that tube is filled with an arc-quenching filler material 176, At such time, the tubular Washer 171 is telescoped over the other end of the fusible conductor 172 and into the other end of the tube 168. Thereupon, solder is used to bond the tubular washer 171 to the other end of the tube 168 and to the other end of `the fusible conductor 172. The tube 168, the tubular washers 170 and 171, and the fusible conductor 172 will constitute a hermetically-sealed cartridge.

That hermetically-sealed cartridge will then be disposed so the outer faces of the tubular washers 170 and 171 abut the confronting faces of the cup-shaped washers 153 and 166. At such time, lower-melting point solder 174 will be used to bond that cartridge to the two terminals for the fuse of FIG. 7. That cartridge and those terminals will constitute a rugged subassembly which can be telescoped within the housing 140. After one end of that sub-assembly has been telescoped into the housing 140, while that housing is held in a vertical position, and while the other end of that sub-assembly is close to the upper end of that housing, sand 1169 will be introduced into that upper end of that 4housing to lill the space between that sub-assembly and the interior of that housing. Thereafter, that subassembly will be fully telescoped into the position shown by FIG. 7. At such time, the pins 178 and 180 will be forced inwardly through openings in the housing 140 into sockets 150 in the Washers 148 and 160.

The various terminals provided by the present invention are easily and inexpensively made. Further, those terminals can be made quite light in weight, as shown by FIGS. 5 and 6.

Whereas the drawing and accompanying description have shown and described several preferred embodiments of the present invention it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

1. A wholly-enclosed, vent-less, one-time electric fuse which comprises:

(a) a housing of insulating material that is cylindrical in configuration, that has open ends, and that is imperforate intermediate said open ends,

(b) ametal terminal,

(c) said terminal having a generally-flat portion with a reduced-width inner end,

(d) said terminal having a plurality of stiff metal washers with centrally-located openings that are telescoped over said reduced-width inner end of said generally-flat portion of said terminal,

(e) said Washers being disposed in face-to-face engagement, having readily-bondable confronting faces, and coacting with said generally-flat portion to constitute a relatively massive terminal,

(f) said Washers and said reduced-width inner end of said terminal being disposed within one end of said housing, and said relatively-flat portion of said terminal projecting outwardly beyond said one end of said housing,

(g) the innermost of said washers having a plurality of shallow circumferentially-spaced indentations therein,

(h) some of said washers having weight-reducing openings therein that are intermediate the peripheries and the centrally-located openings thereof,

(i) interacting surfaces on said reduced-Width inner end of said terminal and on at least one of said Washers to mechanically-secure and electricallyconductive bonding material in engagement with said reduced-width inner end of said terminal and also in engagement with said readily-bondable confronting faces of said washers to electrically-bond, said washers to each other and to said reduced-width inner end of said generally-flat portion of said terminal,

(j) a plurality of said washers having diameters that are just slightly smaller than the inner diameter of said one end of said housing,

(k) whereby said terminal substantially closes said one end of said housing whenever said washers of said terminal are disposed within said one end of said housing,

(l) a second metal terminal,

(m) said second terminal having a generally-flat portion with a reduced-width inner end,

(n) said second terminal having a plurality of stiff metal washers with centrally-located openings that are telescoped over said reduced-width inner end of said generally-flat portion of said second terminal,

(o) said washers of said second terminal being disposed in face-to-face engagement, having readilybondable confronting faces, and coacting with said generally-Hat portion of said second terminal to constitute a second relatively massive terminal,

(p) said washers and said reduced-Width inner end of said second terminal being disposed within the other end of said housing, and said relatively-flat portion of said second terminal projecting outwardly beyond said other end of said housing,

(q) the innermost of said washers of said second terminal having a plurality of shallow circumferentially-spaced indentations therein,

(r) said shallow indentations in said innermost washer of said-second terminal being in register with said indentations in said innermost washer of the first said terminal,

(s) some of said washers of said second terminal having Weight-reducing openings therein that are intermediate the peripheries and the centrally-located openings thereof,

k(t) interacting surfaces on said reduced-width inner end of said second terminal and on at least one of said washers of said second terminal to mechanically-secure, and electrically-conductive bonding material in engagement with said reduced-widthI inner end of said second terminal and also in engagement with said readily-bondable confronting faces of said washers to electrically-bond, said washers to each other and to said reduced-width inner end of said generally-flat portion of said second terminal,

(u) a plurality of said washers of said second terminal having diameters that are just slightly smaller than the inner diameter of the other end 0f said housing,

(v) whereby said second terminal substantially closes said other end of said housing whenever said Washers of said second terminal are disposed within said other end of said housing,

(w) said washers of said second terminal having aligned openings therein to define a passage through said second terminal,

(X) a self-tapping metal plug disposed within said passage in said second terminal to close and seal said passage,

(y) one of said washers lof the first said terminal having a diameter apreciably smaller than the inner diameter of said one end of said housing,

(z) said one washer of the first said terminal coacting with two abutting washers of the first said terminal to define an anular recess,

(aa) an O-ring disposed within said annular recess that simultaneously engages said one washer and vsaid .abutting washers of the first said terminal and the inner surface of said one end of said housing to provide a seal between the first said terminal and said housing,

(ab) one of said washers of said second terminal having a diameter apreciably smaller than the inner diameter of said other end of said housing,

(ac) said one washer of said second terminal coacting with two abutting washers of said second terminal to define a second anular recess,

(ad) a second O-ring disposed within said second annular recess that simultaneously engages said one washer and said abutting washers of said second terminal and the inner surface of said other end of said housing to provide a seal between said second terminal and said housing,

(ae) a plurality of fusible conductors disposed within said housing and having the ends thereof extending into said shallow indentations in said innermost washers of the rst said and said second terminals,

(af) electrically-conductive material bonding further said ends of said fusible conductors within said indentations in said innermost washers of the first said and said second terminals,

(ag) arc-extinguishing filler material disposed within said housing and surrounding and engaging said fusible conductors,

(ah) sockets in the peripheries of the first said and said second terminals, and

(ai) pins extending through openings in said housing and seated within said sockets in the first said and said second terminals to hold said terminals in assembled relation with said housing.

(aj) said centrally-located openings in said washers automatically positioning said reduced-width inner ends of said terminals relative to the peripheries of said washers,

(ak) the telescoping of said washers over said reducedwidth inner ends of said terminals providing full resistance to any forces tending to bend said generally-ilat portions of said terminals relative to said washers,

(al) said further electrically-conductive material, said washers, and said electrically-conductive bonding material coacting to provide the current paths for current flowing from the first said terminal to said fusible conductors and thence to said second terminal.

2. A wholly-enclosed, vent-less, one-time electric fuse which comprises:

(a) a housing of insulating material, that has open ends, and that is imperforate immediate said open ends,

(b) ametal terminal,

(c) said terminal having a generally-flat portion with a reduced-width inner end,

(d) said terminal having a plurality of stiff metal washers with centrally-located openings that are telescoped over said reduced-width inner end of said generally-flat portion of said terminal,

(e) said washers being disposed in face-to-face engagement and having readily-'bondable confronting faces,

(f) said washers and said reduced-width inner end of said terminal being disposed within one end of said housing, and said relatively-fiat portion of said terminal projecting outwardly beyond said one end of said housing,

(g) interacting surfaces on said reduced-width inner end of said terminal and on at least one of said washers to mechanically-secure, and electricallyconductive bonding material in engagement with said reduced-width inner end of said terminal and also in engagement with said readily-bondable confronting faces of said washers to electrically-bond, said washers to each other and to said reducedwidth inner end of said generally-flat portion of said terminal,

(h) a plurality of said washers having diameters that are just slightly smaller than the inner diameter of said one end of said housing,

(i) whereby said terminal substantially closes said `one end of said housing whenever said washers of said terminal are disposed within said one end of said housing,

(j) a second metal terminal,

(k) said second terminal having a generally-fiat portion with a reduced-width inner end,

(l) said second terminal having a plurality of stiff metal washers with centrally-located openings that are telescoped over said reduced-width inner end of said generally-flat portion of said second terminal,

(m),said washers of said second terminal being disposed in face-to-face engagement and having readilybondable confronting faces,

(n) said washers and said reduced width inner end of said second terminal being disposed within the other end of said housing, and said relatively-flat portion of said second terminal projecting outwardly beyond said other end of said housing,

(o) interacting surfaces on said reduced-width inner end of said second terminal and on at least one of said washers of said second terminal to mechanically-secure, and electrically-conductive bonding material in engagement with, said reduced-width inner end of said second terminal and also in engagement with said readily-bondable confronting faces of said washers to electrically-bond, said washers to each other and to said reduced-width inner end of said generally-flat portion `of said second terminal,

(p) a plurality of said washers of said second terminal having diameters that are just slightly smaller than the inner diameter of the other end of said housing,

(q) whereby said second terminal substantially closes said other end of said housing whenever said washers lof said second terminal are disposed within said other end of said housing,

(r) some of said washers having weight-reducing openings therein that are intermediate the peripheries and the centrally-located openings thereof,

(s) a fusible conductor disposed within said housing and having the ends thereof extending to said innermost washers of the first said and said second terminals, and

(t) electrically-conductive material bonding further said ends of said fusible conductor to Said innermost washers of the first said and said second terminals,

(u) said centrally-located openings in said washers automatically positioning said reduced-width inner ends of said terminals relative to the peripheries of said Washers,

(v) the telescoping of said washers over said reducedwidth inner ends of said terminals providing full resistance to any forces tending to bend said generally-flat portions of said terminals relative to said washers,

(w) said further electrically-conductive material, said washers, and said electrically-conductive bonding material coacting to provide the current path for current flowing from the first said terminal to said fusible conductor and thence to said second terminal.

3. A wholly-enclosed, vent-less, one-time electric fuse which comprises:

(a) a housing of insulating material, that has open ends, and that is imperforate intermediate said open ends,

(b) ametal terminal,

(c) said terminal having a generally-flat portion with a reduced-width inner end,

(d) said terminal having a plurality of stiff metal washers with centrally-located lopenings that are telescoped over said reduced-width inner end of said generally-flat portion of said terminal,

(e) said washers being disposed in face-to-face engagement and having readily-bondable confronting faces,

(f) said washers and said reduced-width inner end of said terminal being disposed within one end of said housing, and said relatively-flat portion of said terminal projecting outwardly beyond said one end of said housing,

(g) interacting surfaces on said reduced-width inner end of said terminal and on at least one of said 4washers to mechanically-secure, and electricallyconductive bonding material in engagement with said reduced-width inner end of said terminal and also in engagement with said readily-bondable confronting faces of said washers to electrically-bond, said washers to each other and to said reducedwidth inner end Iof said generally-flat portion of said terminal,

(h) a plurality of said Washers having diameters that are just slightly smaller than the inner diameter of said one end of said housing,

(i) whereby said terminal substantially closes said one end of said housing whenever said washers of said terminal are disposed within said one end of said housing,

(j) a second metal terminal,

(k) said second terminal having a generally-flat portion with a reduced-width inner end,

(l) said second terminal having a plurality of stiff metal washers with centrally-locatedopenings that are telescoped over said reduced-width inner end of said generally-flat portion of said second terminal,

(m) said washers of said second terminal being disposed in face-to-face engagement and having readilybondable confronting faces,

(n) said washers and said reduced-width inner end of said second terminal being disposed within the other end of said housing, and said relatively-flat portion of said second terminal projecting outwardly beyond said other end of said housing,

(o) interacting surfaces on said reduced-width inner end of said second terminal and on at least one of said washers of said second terminal to mechanically-secure, and electrically-conductive bonding material in engagement with said reduced-width inner end of said second terminal and also in engagement with said readily-bondable confronting faces of said washers to electrically-bond, said washers to each other and to said reduced-width inner end of said generally-flat portion of said second terminal,

(p) a plurality of said washers of said second terminal having diameters that are just slightly smaller than the inner diameter of the other end of said housing,

(q) whereby said second terminal substantially closes said other end of said housing whenever said washers of said second terminal are disposed within said other end of said housing,

(r) a fusible conductor within said housing that is electrically connected to the innermost washers of the rst said and said second terminals,

(s) said centrally-located openings in said washers automatically positioning said reduced-width inner ends of said terminals relative to the peripheries of said washers,

(t) the telescoping of said washers over said reducedwidth inner ends of said terminals providing full resistance to any forces tending to bend said generally-flat portions of said terminals relative to said washers,

(u) said washers and said electrically-conductive bonding material coacting to provide the current path for current flowing from the first said terminal to said fusible conductor and thence to said second terminal.

References Cited by the Examiner UNITED STATES PATENTS 1,061,228 5/1913 Daum 200-132 1,062,240 5/ 1913 Kaiser 200-132 1,793,318 2/1931 Hopkins 200-132 2,071,435 2/ 1937 Saudicoeur 200-131 X 2,166,174 7/ 1939 Popp 200-131 2,308,435 1/1943 Wood 200131 2,497,227 2/ 1950 Messer et al. 200-131 2,837,614 6/1958 Fister 200-120 2,934,628 4/ 1960 Massar et al. 200-142 3,041,428 6/ 1962 Sommers 200-131 BERNARD A. GILHEANY, Primary Examiner. H. GILSON, Assistant Examiner. 

1. A WHOLLY-ENCLOSED, VENT-LESS, ONE-TIME ELECTRIC FUSE WHICH COMPRISES: (A) A HOUSING OF INSULATING MATERIAL THAT IS CYLINDRICAL IN CONFIGURATION, THAT HAS OPEN ENDS, AND THAT IS IMPERFORATE INTERMEDIATE SAID OPEN ENDS, (B) A METAL TERMINAL, (C) SAID TERMINAL HAVING A GENERALLY-FLAT PORTION WITH A REDUCED-WIDTH INNER END, (D) SAID TERMINAL HAVING A PLURALITY OF STIFF METAL WASHERS WITH CENTRALLY-LOCATED OPENINGS THAT ARE TELESCOPED OVER SAID REDUCED-WIDTH INNER END OF SAID GENERALLY-FLAT PORTION OF SAID TERMINAL, (E) SAID WASHERS BEING DISPOSED IN FACE-TO-FACE ENGAGEMENT, HAVING READILY-BONDABLE CONFRONTING FACES, AND COACTING WITH SAID GENERALLY-FLAT PORTION TO CONSTITUTE A RELATIVELY MASSIVE TERMINAL, (F) SAID WASHERS AND SAID REDUCED-WIDTH INNER END OF SAID TERMINAL BEING DISPOSED WITHIN ONE END OF SAID HOUSING, AND SAID RELATIVELY-FLAT PORTION OF SAID TERMINAL PROJECTING OUTWARDLY BEYOND SAID ONE END OF SAID HOUSING, (G) THE INNERMOST OF SAID WASHERS HAVING A PLURALITY OF SHALLOW CIRCUMFERENTIALLY-SPACED INDENTATIONS THEREIN, (H) SOME OF SAID WASHERS HAVING WEIGHT-REDUCING OPENINGS THEREIN THAT ARE INTERMEDIATE THE PERIPHERIES AND THE CENTRALLY-LOCATED OPENINGS THEREOF, (I) INTERACTING SURFACES ON SAID REDUCED-WIDTH INNER END OF SAID TERMINAL AND ON AT LEAST ONE OF SAID WASHERS TO MECHANICALLY-SECURE AND ELECTRICALLYCONDUCTIVE BONDING MATERIAL IN ENGAGEMENT WITH SAID REDUCED-WIDTH INNER END OF SAID TERMINAL AND ALSO IN ENGAGEMENT WITH SAID READILY-BONDABLE CONFRONTING FACES OF SAID WASHERS TO ELECTRICALLY-BOND, SAID WASHERS TO EACH OTHER AND TO SAID REDUCED-WIDTH INNER END OF SAID GENERALLY-FLAT PORTION OF SAID TERMINAL, (J) A PLURALITY OF SAID WASHERS HAVING DIAMETERS THAT ARE JUST SLIGHTLY SMALLER THAN THE INNER DIAMETER OF SAID ONE END OF SAID HOUSING, (K) WHEREBY SAID TERMINAL SUBSTANTIALLY CLOSES SAID ONE END OF SAID HOUSING WHENEVER SAID WASHERS OF SAID TERMINAL ARE DISPOSED WITHIN SAID ONE END OF SAID HOUSING, (L) A SECOND METAL TERMINAL, (M) SAID SECOND TERMINAL HAVING A GENERALLY-FLAT PORTION WITH A REDUCED-WIDTH INNER END, (N) SAID SECOND TERMINAL HAVING A PLURALITY OF STIFF METAL WASHERS WITH CENTRALLY-LOCATED OPENINGS THAT ARE TELESCOPED OVER SAID REDUCED-WIDTH INNER END OF SAID GENERALLY-FLAT PORTION OF SAID SECOND TERMINAL, (O) SAID WASHERS OF SAID SECOND TERMINAL BEING DISPOSED IN FACE-TO-FACE ENGAGEMENT, HAVING READILYBONDABLE CONFRONTING FACES, AND COACTING WITH SAID GENERALLY-FLAT PORTION OF SAID SECOND TERMINAL TO CONSTITUTE A SECOND RELATIVELY MASSIVE TERMINAL, (P) SAID WASHERS AND SAID REDUCED-WIDTH INNER END OF SAID SECOND TERMINAL BEING DISPOSED WITHIN THE OTHER END OF SAID HOUSING, AND SAID RELATIVELY-FLAT PORTION OF SAID SECOND TERMINAL PROJECTING OUTWARDLY BEYOND SAID OTHER END OF SAID HOUSING, (Q) THE INNERMOST OF SAID WASHERS OF SAID SECOND TERMINAL HAVING A PLURALITY OF SHALLOW CIRCUMFERENTIALLY-SPACED INDENTATIONS THEREIN, (R) SAID SHALLOW INDENTATIONS IN SAID INNERMOST WASHER OF SAID SECOND TERMINAL BEING IN REGISTER WITH SAID INDENTATIONS IN SAID INNERMOST WASHER OF THE FIRST SAID TERMINAL, (S) SOME OF SAID WASHERS OF SAID SECOND TERMINAL HAVING WEIGHT-REDUCING OPENINGS THEREIN THAT ARE INTERMEDIATE THE PERIPHERIES AND THE CENTRALLY-LOCATED OPENINGS THEREOF, (T) INTERACTING SURFACES ON SAID REDCED-WIDTH INNER END OF SAID SECOND TERMINAL AND ON AT LEAST ONE OF SAID WASHERS OF SAID SECOND TERMINAL TO MECHANICALLY-SECURE, AND ELECTRICALLY-CONDUCTIVE BONDING MATERIAL IN ENGAGEMENT WITH SAID REDUCED-WIDTH INNER END OF SAID SECOND TERMINAL AND ALSO IN ENGAGEMENT WITH SAID READILY-BONDABLE CONFRONTING FACES OF SAID WASHERS TO ELECTRICALLY-BOND, SAID WASHERS TO EACH OTHER AND TO SAID REDUCED-WIDTH INNER END OF SAID GENERALLY-FLAT PORTION OF SAID SECOND TERMINAL, (U) A PLURALITY OF SAID WASHERS OF SAID SECOND TERMINAL HAVING DIAMETERS THAT ARE JUST SLIGHTLY SMALLER THAN THE INNER DIAMETER OF THE OTHER END OF SAID HOUSING, (V) WHEREBY SAID SECOND TERMINAL SUBSTANTIALLY CLOSES SAID OTHER END OF SAID HOUSING WHENEVER SAID WASHERS OF SAID SECOND TERMINAL ARE DISPOSED WITHIN SAID OTHER END OF SAID HOUSING, (W) SAID WASHERS OF SAID SECOND TERMINAL HAVING ALIGNED OPENINGS THEREIN TO DEFINE A PASSAGE THROUGH SAID SECOND TERMINAL, (X) A SELF-TAPPING METAL PLUG DISPOSED WITHIN SAID PASSAGE IN SAID SECOND TERMINAL TO CLOSE AND SEAL SAID PASSAGE, (Y) ONE OF SAID WASHERS OF THE FIRST SAID TERMINAL HAVING A DIAMETER APPRECIABLY SMALLER THAN THE INNER DIAMETER OF SAID ONE END OF SAID HOUSING, (Z) SAID ONE WASHER OF THE FIRST SAID TERMINAL COACTING WITH TWO ABUTTING WASHERS OF THE FIRST SAID TERMINAL TO DEFINE AN ANNULAR RECESS, (AA) AN O-RING DISPOSED WITHIN SAID ANNULAR RECESS THAT SIMULTANEOSLY ENGAGES SAID ONE WASHER AND SAID ABUTTING WASHERS OF THE FIRST SAID TERMINAL AND THE INNER SURFACE OF SAID ONE END OF SAID HOUSING TO PROVIDE A SEAL BETWEEN THE FIRST SAID TERMINAL AND SAID HOUSING, (AB) ONE OF SAID WASHERS OF SAID SECOND TERMINAL HAVING A DIAMETER APPRECIABLY SMALLER THAN THE INNER DIAMETER OF SAID OTHER END OF SAID HOUSING, (AC) SAID ONE WASHER OF SAID SECOND TERMINAL COACTING WITH TWO ABUTTING WASHERS OF SAID SECOND TERMINAL TO DEFINE A SECOND ANULAR RECESS, (AD) A SECOND O-RING DISPOSED WITHIN SAID SECOND ANNULAR RECESS THAT SIMULTANEOUSLY ENGAGES SAID ONE WASHER AND SAID ABUTTING WASHERS OF SAID SECOND TERMINAL AND THE INNER SURFACE OF SAID OTHER END OF SAID HOUSING TO PROVIDE A SEAL BETWEEN SAID SECOND TERMINAL AND SAID HOUSING, (AE) A PLURALITY OF FUSIBLE CONDUCTORS DISPOSED WITHIN SAID HOUSING AND HAVING THE ENDS THEREOF EXTENDING INTO SAID SHALLOW INDENTATIONS IN SAID INNERMOST WASHERS OF THE FIRST SAID AND SAID SECOND TERMINALS, (AF) ELECTRICALLY-CONDUCTIVE MATERIAL BONDING FURTHER SAID ENDS OF SAID FUSIBLE CONDUCTORS WITHIN SAID INDENTATIONS IN SAID INNERMOST WASHERS OF THE FIRST SAID AND SAID SECOND TERMINALS, (AG) ARC-EXTINGUISHING FILLER MATERIAL DISPOSED WITHIN SAID HOUSING AND SURROUNDING AND ENGAGING SAID FUSIBLE CONDUCTORS, (AH) SOCKETS IN THE PERIPHERIES OF THE FIRST SAID AND SAID SECOND TERMINALS, AND (AI) PINS EXTENDING THROUGH OPENINGS IN SAID HOUSING AND SEATED WITHIN SAID SOCKETS IN THE FIRST SAID AND SAID SECOND TERMINALS TO HOLD SAID TERMINALS IN ASSEMBLED RELATION WITH SAID HOUSING. (AJ) SAID CENTRALLY-LOCATED OPENINGS IN SAID WASHERS AUTOMATICALLY POSITIONING SAID REDUCED-WIDTH INNER ENDS OF SAID TERMINALS RELATIVE TO THE PERIPHERIES OF SAID WASHERS, (AK) THE TELESCOPING OF SAID WASHERS OVER SAID REDUCEDWIDTH INNER ENDS OF SAID TERMINALS PROVIDING FULL RESISTANCE TO ANY FORCES TENDING TO BEND SAID GENERALLY-FLAT PORTIONS OF SAID TERMINALS RELATIVE TO SAID WASHERS, (AL) SAID FURTHER ELECTRICALLY-CONDUCTIVE MATERIAL, SAID WASHERS, AND SAID ELECTRICALLY-CONDUCTIVE BONDING MATERIAL COACTING TO PROVIDE THE CURRENT PATHS FOR CURRENT FLOWING FROM THE FIRST SAID TERMINAL TO SAID FUSIBLE CONDUCTORS AND THENCE TO SAID SECOND TERMINAL. 